Corrugating die



Oct. 19, 1943. F. P. IBUCKLEIN 2,332,435

CORRUGA'IING DIE Filed Au 27, 1940' 2 She'ets-Sheet 1 .Z'NVENTOR (LU- M-Oct. 19, 1943. F. P. BUCKLEIN CORRUGATING DIE Filed Aug. 27, 1940 2Sheets-Sheet 2 INVENTOR Patented Oct. 19, 1-943 I Frank'Pf'Itucklein,Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank,

Calif "A'p'mmat on Augu t. 27, 1:540; s ial No; 354,343

'7 Claims. (ar as-icy I This invention relates tofim proved formingdies; I

for use on simple orsingle acting power presses such as for example thepress, brakes used for sheet metal. To this end I have provided acompound, progressive die set to develop the final shape desired in thematerial being worked upon.

The die set chosen for illustrative purposesv is adapted to form aseries of non-sinusoidal ,corrugations in sheet material, the finishedinaterial being used as reinforcement beneath the stressed skin coveringof airplane wings. forming such reinforcing material the blank sheet hasheretofore been supplied with locatingholes or notches fitting over pinson a mandrel, over which a properly formed member is forced to producethe desired shape. In so producing cor-g. rugations the locating holes,or notches are a source of trouble and delay, andthe inherentspringback of high strength material has also been a problem, incebending sheet material,

without stretching or drawing beyond its yield I cessive operations informing a single corrugation [4 in a sheet metal blank I5 it will becon- ,venient to describe the separate set-upsfor the point, results inunpredictable springback, which varies with the thickness, temper andelasticity of the material. In order to accurately form' thecorrugations without appreciable stretch, and

consequent thinning of the material,I provide,

a multiple station die set wherein an initial overbend is produced inthe material by a semi-folding operation; as distinguished from adrawing operation; in order to allow for subsequent springback uponrelease from the die, and subsequently utilize a spring pressed plungerto, act

I Figure II is a fragmentary longitudinal section on the lineII-JI ofFigure I showing the supporting springs and guide pins. I Figure III i asection of the lines III III' of Figure II, in the; plane of one of thespring locations. H 1 i Figures IV to-VII, inclusive, correspond't'othestagesin the operation of the .dies.

Asshown; i The dies of this invention are intended to '1be used inconventional single acting power presses 1. line IV--IV in Figure II,and show successive or sheet metal press brakes, sothatto simplify thedisclosure no further reference will be made to the press or brake, .Alower or female die is built up one baseblock Hlhaving af'locatingkey Hfor aligning it in the'press bed; ,and;a cooperating maledie has a baseblock II with a hooked key 13 for fastening the 's arne]to' the movablehead or ramof the press. I

Since the die,; as disclosed, performs two suctwo steps. To thisenitheinitial forminglmechanism will be first described. The female baseblock! yieldingly supports a die block lfi by means of springs ll, guidepins [8 serving to as 'a hold-down While another corrugation is ,be-

, ing formed by the semi-folding operation.

It is accordingly anobject of this invention to provide'an improved diefor sequentially forming a series of corrugations in sheet material, .it

being evident that while such corrugations will normally be madeparallelto each other, in air: plane wing construction it may be.advantageous to taper thev corrugations and/or slightly converge. themfor use in Wings of tapered profile.

It is a further object of this invention to provide an improved die foruse on simple presses or brakes that will accurately and reproduceablyform the desired profile without stretching and.

thinning the material as a result of drawing op erations. I J Other andfurther important objects "of this invention will be apparent from thedisclosures in thespecification and the accompanying drawings. i

This invention in its preferred formis illustrated in the drawings andhereinafter more fully described. 1 4

In the drawings: I

Figure I is a fragmentary perspective view of adie set embodying thefeatures of thisinvention, the length of the dies being'limited only bythe size of the press or brake with which it is to be used.

limit the movement of the block I6, The block |6 is provided with pivotsl 9for a lever 20 whichv is swung upwardly by theclosingordownwardmovement of theblock 16 relative to the base 0. The block 1 i3 carries asuitably, shaped member 2| which defines the corner to be produced onthe sheet metal blank, and the lever 2t supports a similar me mber 22.which defines. the ,othercorner of the corrugation l4; the upward swingof the lever 20 serving to fold the sheet material about a former23-1Whi0h, is pivotally suspended frornthe male base block l2. Both'corners 2| and 22 and theformer 23 are of less radius than the finalshape of the corrugation,

and allow for springback. The corner member 22 is supported and backedby adjustable shims 24 which control the degree of overbend given thesheet. Also,"removal of the supporting shim will allow an offset foroverlapping the edges of adjacent sheets of corrugated material. Theformer 23 is preferably permitted a slight lateral motion, as indicatedby the dotted outline infigure VI, as it is subjectto sidepressurefrointhe sheet material during the closing movement of the die,both before and after the lever 20 is shifted to fold the material intothe position of Figure v11. This also helps to feed the sheet materialinto" the desired shape, rather than to stretch it duringthe formingoperation] When the dies are fully closed, with the lever Ml-forced,upward, the corner memlber 22 on the leveroforces the sheet material atan angle against a land on the upper'o'r male die. It will be noted thatthe corner piece 2|.

the movable side wall formed by the lever 20 and the corner member 22serves to wrap the sheet material about. .the plunger, bending .itthrough more than a half circle, as indicated in Figure VII. The extentof overbending required, 5 may vary with different materials and tempersbut is so proportioned that the natural spring-- back or openingmovement will result in the dea; sired final form. V i 0 The hold-downmechanism comprises a plunger 26 formed to cooperate with acomplementary 7 channel 21 in the female die I6, the plunger beingcarried by a plate 28 movable relative to the male base block and backedby springs 29, which springs are of less number and strength than thesprings inthe lower dieso'that theplunger 26 wil1 be seated andcompressing the previously formed corrugation before the female die iscompressed. The plunger 26 is removable in case itis desired to manuallycontrol the positioning of the material to produce parallel orconverging spacing in the material between or adjacent one or morecorrugations, in which case the material would be fed from the right. Atthe same time as: the plunger is seated in the female die 16, the' plate28 bears againstlands 30 on either side'of the channel 21 so that theplate and plunger serve as hold-downs while the first describedlparts of"the dies are forming another corrugation: The action is a clamping one,as 30 distinguished from a drawing operation wherein the material feedsunder the hold-down. The plate 28 and-plunger 26 have guide pins 3! and32 slideable in suitable recesses in the male base-i: block l2, theguide pins -32 having heads limiting 35 the stroke of the plate andplunger.

Figures IV to VII inclusive illustrate successive stages in theoperation of the die, Figure IV illustrating theinitial position with aDre- 1f? formed corrugation 14 in the sheet metal blank l5' positionedinthe channel 21 to be engaged by the plunger 26 as indicated in FigureV, with theplate 28 pressing the material against the lands 30 on eitherside of the-channel. Duringqq; continued downward movement of the upperor male die the springs 29 back of the plate 28 are compressed and serveto hold the sheetmaterial while the former 23 bends the material overThis bending 'operationct produces reversible side thrust on the formerwhile the sheet is being deformed sufficiently to wrap about the form.During this operation the. material feeds over the corner 22 until thedies bottom andforce the lever 20 upwardly and inwardly to appreciablyoverbend the material as indicated in Figure -VII. i V a While the dieset chosen for illustrative purposes is particularly adapted to formcorrugated reinforcing sheets for aircraft purposes, it is evident thatmy invention is adapted to a wide field of usefulness, particularly inhandling impressions in materials that are ordinarily hard to handle inbending operations where it is not desired to stretchthe material.

Having thus described my invention and the 5 present preferredembodiments thereof, I desire to emphasize the fact that manymodifications may be resorted to in a manner limited only by a justinterpretation of the following claims} I claim;

1. In a corrugating mechanism of the classdescribed, a base block andan, associated female die, a bending member pivoted to said female dieand having an outwardly extending portion, and an arcuate upwardlyextending portion, said first named portion being engaged with the baseblOCktO provide a fulcrum contact, an opposed base block and. anassociated male die, means to yieldably support said dies on the blocks,a second bending member pivotally supported on said opposed base blockin positions to cooperate re spectivelywith the female die and the firstnamed bending. member, whereby the male die will engage. andrnove thefemale die towards its base block and simultaneously cause the femalebending member to rotate around its fulcrum contact towards the femaledie, to engage a Work piece.

2. Ina mechanism as set forth in claim I, wherein the yieldable meansthat support the dies on; the 'respective base Pblocks comprise springsacting to force each die away from its respectivebase blockf 9 In amechanism "as set forth in claim 1, wherein the base block thatsupportsthe bending member is formed to provide a land portion adjacent-thebending member, said land portion being operative to engage and bend thematerial worked on adjacent the bending member.

4;]111 a mechanism as set forth in claim 1,

wherein the terminal free end of the second named bending member isprovided with an adjustabletip portion and means 'for adjusting said tipportion relative to. the body portion of the said bending member tocontrolthe degree of bend made in a sheet worked on';

5. In acorruga'ting mechanism of the class described, in combination, apair of base blocks,

male and female forming members supported res'pectively on said baseblocks, cushioning means "associated with each block and being yieldablefor movement of each forming member towards itsrespec'tive base "block,a bending member pivota'lly supported on the block which carries themale forming' memb'er, a second bending member fulcrumedon the femaleforming member and extended to contact the adjacent base block,

and meanson the supporting base block to engage the second named bendingmember to more the latter member towards the female forming member inresponse to relative movement of said last 'named member onits baseblo'ck'to form a corrugation in the Work piece;

6. In a mechanisin of the class described in combination, a base block,a female holding die 'swing towardstheffemale holding dieya second .baseblockfa male holding die andaa male bend- -ing die carriedby said secondbase blo'cl; and

positioned thereon to respectively engage'the female'holding' die andthe female .bendingdie.

$7. In a device asset forth in claim fi, spring means positioned betweenthe malekholding die and its supporting base block, said spring meansbeing weaker than the spring means between the female die'member and itssupporting block whereby, when the male holding die is moved to engage awork piece between the femaleholdingdie' and the male holding die,saidmale holding diewill be'moved axljacent'its supporting block priorto any movement of the female holding die.

. FRANK P. BUCKLEIN

